Why Does This Strange Anomaly Happen.

[TheCuriousMind]

Audio is loud, muted the video  

Before we get started, I wanted to say that I am no expert and nor do I claim to be an expert in any kind of science. I'm only curious and if anyone could provide to me a Well-established explanation. This would be great, maybe I have made a bigger deal out of something that isn't really that important. 

 

I want to clarify that the anomaly happening in this video was first discovered on accident without recording from a secondary phone.

I First noticed it purely from my own eyes.

(The Anomaly) 

One evening when I was texting, I noticed as my fingers came close to the words on my phones keyboard, a very strange and interesting anomaly would happen.

The words on my phones keyboard seemed to move towards my fingers sometimes in a very exaggerated way, it was very puzzling to me.

 

(My First Question

So, I thought to myself for a few moments, I then asked was this "effect" just an illusion that had something to do with the way my brain was Interpreting the information given to it from the way my eyes were receiving the light?

I needed a way to test this so here is my best thought. 😅

(My Second Question + Experiment)

I asked Myself, would the same thing happen with a camera, could this be replicated outside of the biological sensory perception (SIGHT)

I wanted to see if I could replicate the same anomaly that I was seeing, but on a capture device, effectively eliminating the the first question, right?

So, I grabbed a secondary phone.  

Anyone wanting to replicate this does not need a phone, but only the use of their working eyes. 

(What I discovered)

This happens when both, the Background aka the (Text on screen) and the (Finger), are both slightly out of focus.

But why does this cause this anomaly to occur?

And so here I am 😅

[Lorentz Jr]

This happens to me if I hold my phone close and let my eyes go out of focus. When I wear reading glasses and keep the letters in focus, it doesn't happen.

And it happens to your camera too, so it sounds like distortion from the lens. But why does it only affect the letters and not the finger? Refraction should move the letters the other way, away from the finger. Very strange.

Unless it really is some weird thing where the brain misinterprets the line of the letter when it's close to another edge and the image is fuzzy. It's not the angle though. at 0:17 and 0:19, the whole j and one whole side of the u move toward the finger.

Edited December 23, 2022 by Lorentz Jr

[Genady]

Does it happen if you replace the finger with say a pencil, a chopstick, etc.? 

[Lorentz Jr]

3 hours ago, Genady said:

Does it happen if you replace the finger with say a pencil, a chopstick, etc.? 

Yes, I think so. I'm actually running into reproducibility problems (😡), maybe getting tired, I don't know. But it did work with an eraser, so I doubt it's air near the finger being heated. We'll see what the OP says.

I seem to develop some kind of double vision when I blur my eyes, so there's a second image of the letter that shows "through" the sliver of one of the images of the object in front of it that sticks out past the other image. Sometimes the letter is skewed, sometimes it's not.

It also seems to work with printed text on paper (although that's trickier because of shadows), so I guess it's not related to the phone screen.

Edited December 23, 2022 by Lorentz Jr

[joigus]

It happens because of diffraction of light. When light goes past a sharp edge, the trajectory of light rays differs significantly from that of a straight line. The effect generally depends on the light frequency and the typical sizes of the objects involved, as well as the refraction index of the medium that carries the waves. If the source light is bluer, the effect should be less noticeable for objects of the same size, while if the source light is redder, the result should be more noticeable.

Diffraction has many similar or related effects associated to it.

A nice analogy to understand this qualitatively is provided by sound. As sound has much much longer wavelenghts than typical light --say, visible light--, it can turn corners, so you can hear someone speak even though there are obstacles standing in the way. Diffraction of sound also explains that in Greek theaters you could hear the actors declaiming as if they were next to you, even though they may be many metres away.

Analysing diffraction properly is a complicated problem mathematically. In this case, it seems that, instead of seeing the image behind the finger, what happens is the opposite.

The take-home message is: Waves can do funny things around corners.

[Lorentz Jr]

Diffraction should move the image away from the obstacle, not toward it. (Also, I should have said "Diffraction" in my first post, not "Refraction". 🙄)

Light that would have reached the observer in a straight line gets redirected, so the observer doesn't see it. What the observer sees is slightly less diffracted beams that don't pass quite so close to the obstacle.

Edited December 23, 2022 by Lorentz Jr

[TheCuriousMind]

6 hours ago, Genady said:

Does it happen if you replace the finger with say a pencil, a chopstick, etc.? 

Good Question, and it got me on a train of thoughts when I woke up, so I tried a few things and here are the results in the form 2 videos.

 

Changes Made

I was curious if I would achieve the same results with text on paper, I thought maybe it had something to do with the phone light. 

I was also curious about @Genady question, so I used a coloring pencil. 

 

What I Found

I was able to reproduce the effects with a few try's.

I noticed a difference in the way the anomaly behaved, depending on the distance from the camera the closest objects were, in this example the pencil.

In Video Example A, the Camera is about 8 inches away from the pencil and zoomed in, the words were slightly out of focus, and so was the pencil. I was Successfully able to repeat the first anomaly, and if you look closely, the words appear to slightly focus during the anomaly.

 

 

 

 

 

2 hours ago, Lorentz Jr said:

Diffraction should move the image away from the obstacle, not toward it.

 In video Example B: The pencil was but a few Centimeters away from the camera.

But this time instead of the words moving towards the pencil, they moved away, as described with the cause of diffraction. Could Video Example A be the result of something unknown? 

 

 

Why does the change in distance, change the way the camera as well as our own eyes perceive this anomaly? 

Also, it is very early for me so excuse any typos. 

Edited December 23, 2022 by TheCuriousMind

[Genady]

Yes, diffraction does not seem a correct explanation. Can it be tested? (I didn't succeed to reproduce the effect so far. Without glasses I can't say what's happening, while with glasses nothing like that seems to happen.)

[joigus]

Yes, it's probably combined effects of refraction and diffraction. In the case of refraction, light would appear to bend away from the border if the refraction index has the necessary gradient near the surface of the obstacle. The main point being: Light doesn't have to go in a straight line.

I can't contribute anything much now. I'll try to follow, and then maybe comment further.

[Genady]

It looks like being out of focus is a requirement for this phenomenon. Perhaps, there is a key for its explanation.

[Lorentz Jr]

Internal reflection inside the lens????? That still doesn't differentiate between the letters and the finger though.

Edited December 23, 2022 by Lorentz Jr

[Genady]

Optical illusion, akin this?

[TheCuriousMind]

11 hours ago, Genady said:

It looks like being out of focus is a requirement for this phenomenon. Perhaps, there is a key for its explanation.

I would most certainly agree, this is the main key. But its unusual that you can produce a push, or a pull on the words depending on the distance the closest object to the camera is. In these examples it would be the pencil or finger. 

The same effect can be achieved using our eyes though much harder.

Edited December 24, 2022 by TheCuriousMind

[Genady]

The following test might distinguish between an optical effect and an optical illusion. Instead of the finger or pencil, try an object that is of the same color as a background, i.e., something white, maybe just a piece of paper. If it is an optical illusion, the phenomenon will disappear. If it rather is an optical effect, it will be the same.

[mistermack]

I think it's to do with the fact that the nearer object is out of focus, and so is a combination of many images arranged 360 degrees around the main one. So if you hold your finger up in front of your eyes, and focus on the distance, you don't just see one edge of your finger, you see many. 

So when you hold a blurred out-of-focus object against an in-focus object that's further away, the sharper image gets progressively blocked out by the multiple edges of the blurred object, causing the stretching effect. 

[Genady]

I'd expect this to progressively dim parts of the image on the retina. But why would they move? (If they in fact do.)

[mistermack]

2 minutes ago, Genady said:

I'd expect this to progressively dim parts of the image on the retina. But why would they move? (If they in fact do.)

I think thats a result of the blurring, and the fact that the aperture of the lens, or iris, is not a point, but has a substantial diameter, so the image is actually formed from light passing through at slightly varying angles. When that's progressively interfered with, by the out-of-focus image, it causes apparent stretching, and movement of the blurred image causes movement of the in-focus one.

I would think it's a good bet that the bigger the aperture, the more definite the effect. I suppose you could test that by experimenting with various drugs, to open and close your pupils. 😉

[Genady]

16 minutes ago, mistermack said:

II would think it's a good bet that the bigger the aperture, the more definite the effect. I suppose you could test that by experimenting with various drugs, to open and close your pupils. 😉

Or, by doing the same test in different ambient light intensity.

[mistermack]

Just now, Genady said:

Or, by doing the same test in different ambient light intensity.

You could probably test it with an SLR camera in video mode, if it allows setting of the aperture. Compare the effect at maximum and minimum aperture, I would expect it to reduce as the aperture gets smaller. 

[Genady]

Perhaps I am a bad experimentalist. I could not reproduce the effect at all. Anyway, this is what I got. The first pic has F6.3 and the second has F16. The lines look very parallel to me all the time.

[mistermack]

I think that the lines need to be thicker, and the blurred image needs to be at an angle to them. It looks to me like there's a bit of an optical illusion happening, when the image is moving. 

I don't think the lines are bent, but they are progressively obscured by the blurred edge so that it gives the impression of movement and deflection. What happens is that the inside edge of a line gets obscured at an angle, and because you can't see the other edge, it looks like the letter is moving. 

 

[Genady]

I took a snapshot. The line of the "i" appears bent, i.e., not parallel to other "vertical" lines, without a movement.

Here is a "before" picture:

To put the optical illusion possibility finally to rest, I've rotated the image to make "vertical" lines vertical and have added the vertical grid. "i" is obviously not vertical:

[mistermack]

Yes, I agree. I think it's more pronounced when moving, but it does appear bent in the "before" picture. I still think it's an optical illusion brought about by the progressive fuzziness caused by the out-of-focus edge though.

I laid a straight edge ruler over the letter i, lining it up perfectly with the 'i' , and weirdly the ruler is parallel with the lines. Take the ruler away, and the 'i' does look bent. 

[Genady]

You've replied before my last addition in the post above. Here it is:

56 minutes ago, Genady said:

To put the optical illusion possibility finally to rest, I've rotated the image to make "vertical" lines vertical and have added the vertical grid. "i" is obviously not vertical:

 

When the finger is a bit farther away, the letter "i" is definitely vertical:

[mistermack]

Still not convinced. This is what I got with my straight edge :